History of Java

At that time, it was a advanced concept for the green team. But, it was good for internet programming. Later, Netscape Navigator incorporated Java technology.Java history is interesting to know. Java team members (also known as Green Team), initiated a revolutionary task to develop a language for digital devices such as set-top boxes, televisions etc.

James Gosling

Currently, Java is used in internet programming, mobile devices, games, e-business solutions etc. Let's see the major points that describes the history of java.

1) James Gosling, Mike Sheridan, and Patrick Naughton initiated the Java language project in June 1991. The small team of sun engineers called Green Team.

2) Originally designed for small, embedded systems in electronic appliances like set-top boxes.

3) Firstly, it was called "Greentalk" by James Gosling and file extension was .gt.

4) After that, it was called Oak and was developed as a part of the Green project.

5) Why Oak? Oak is a symbol of strength and choosen as a national tree of many countries like U.S.A., France, Germany, Romania etc.

6) In 1995, Oak was renamed as "Java" because it was already a trademark by Oak Technologies.

7) Why they choosed java name for java language? The team gathered to choose a new name. The suggested words were "dynamic", "revolutionary", "Silk", "jolt", "DNA" etc. They wanted something that reflected the essence of the technology: revolutionary, dynamic, lively, cool, unique, and easy to spell and fun to say.

According to James Gosling "Java was one of the top choices along with Silk". Since java was so unique, most of the team members preferred java.

8) Java is an island of Indonesia where first coffee was produced (called java coffee).

9) Notice that Java is just a name not an acronym.

10) Originally developed by James Gosling at Sun Microsystems (which is now a subsidiary of Oracle Corporation) and released in 1995.

11) In 1995, Time magazine called Java one of the Ten Best Products of 1995.

12) JDK 1.0 released in(January 23, 1996).

Java Version History

There are many java versions that has been released.

1. JDK Alpha and Beta (1995)
2. JDK 1.0 (23rd Jan, 1996)
3. JDK 1.1 (19th Feb, 1997)
4. J2SE 1.2 (8th Dec, 1998)
5. J2SE 1.3 (8th May, 2000)
6. J2SE 1.4 (6th Feb, 2002)
7. J2SE 5.0 (30th Sep, 2004)
8. Java SE 6 (11th Dec, 2006)
9. Java SE 7 (28th July, 2011)

JSP Cookies

JSP Cookies Example

         

This tutorial shows how to handle cookies in JSP pages. In this tutorial you will learn how to add cookies through jsp page and then show the value of the same cookie in another JSP page.

Let's understand the cookies. Cookies are short pieces of data sent by web servers to the client browser. The cookies are saved to clients hard disk in the form of small text file. Cookies helps the web servers to identify web users, by this way server tracks the user. Cookies pay very important role in the session tracking.

Cookie Class

In JSP cookie are the object of the class javax.servlet.http.Cookie. This class is used to creates a cookie, a small amount of information sent by a servlet to a Web browser, saved by the browser, and later sent back to the server. A cookie's value can uniquely identify a client, so cookies are commonly used for session management. A cookie has a name, a single value, and optional attributes such as a comment, path and domain qualifiers, a maximum age, and a version number.

The getCookies() method of the request object returns an array of Cookie objects. Cookies can be constructed using the following code:

Cookie(java.lang.String name, java.lang.String value)

Cookie objects have the following methods.

Method	Description
getComment()	Returns the comment describing the purpose of this cookie, or null if no such comment has been defined.
getMaxAge()	Returns the maximum specified age of the cookie.
getName()	Returns the name of the cookie.
getPath()	Returns the prefix of all URLs for which this cookie is targeted.
getValue()	Returns the value of the cookie.
setComment(String)	If a web browser presents this cookie to a user, the cookie's purpose will be described using this comment.
setMaxAge(int)	Sets the maximum age of the cookie. The cookie will expire after that many seconds have passed. Negative values indicate the default behavior: the cookie is not stored persistently, and will be deleted when the user web browser exits. A zero value causes the cookie to be deleted
setPath(String)	This cookie should be presented only with requests beginning with this URL.
setValue(String)	Sets the value of the cookie. Values with various special characters (white space, brackets and parentheses, the equals sign, comma, double quote, slashes, question marks, the "at" sign, colon, and semicolon) should be avoided. Empty values may not behave the same way on all browsers.

Example Using Cookies

No we will write code in JSP file to set and then display the cookie.

Create Form

Here is the code of the form (cookieform.jsp) which prompts the user to enter his/her name.

<%@ page language="java" %> <html> <head> <title>Cookie Input Form</title> </head> <body> <form method="post" action="setcookie.jsp"> <p><b>Enter Your Name: </b><input type="text" name="username"><br> <input type="submit" value="Submit"> </form> </body>

Above form prompts the user to enter the user name. User input are posted to the setcookie.jsp file, which sets the cookie. Here is the code of setcookie.jsp file:

<%@ page language="java" import="java.util.*"%> <% String username=request.getParameter("username"); if(username==null) username=""; Date now = new Date(); String timestamp = now.toString(); Cookie cookie = new Cookie ("username",username); cookie.setMaxAge(365 * 24 * 60 * 60); response.addCookie(cookie); %> <html> <head> <title>Cookie Saved</title> </head> <body> <p><a href="showcookievalue.jsp">Next Page to view the cookie value</a><p> </body>

Above code sets the cookie and then displays a link to view cookie page. Here is the code of display cookie page (showcookievalue.jsp):

<%@ page language="java" %> <% String cookieName = "username"; Cookie cookies [] = request.getCookies (); Cookie myCookie = null; if (cookies != null) { for (int i = 0; i < cookies.length; i++) { if (cookies [i].getName().equals (cookieName)) { myCookie = cookies[i]; break; } } } %> <html> <head> <title>Show Saved Cookie</title> </head> <body> <% if (myCookie == null) { %> No Cookie found with the name <%=cookieName%> <% } else { %> <p>Welcome: <%=myCookie.getValue()%>. <% } %> </body>

When user navigates to the above the page, cookie value is displayed.

JSP Session

This JSP Tutorial shows you how to track the session between different JSP pages. In any web application user moves from one page to another and it becomes necessary to track the user data and objects throughout the application. JSP provide an implicit object "session", which can be use to save the data specific the particular to the user.

In this tutorial we will create an application that takes the user name from the user and then saves into the user session. We will display the saved data to the user in another page.

Here is the code of the JSP file (savenameform.jsp) that takes the input from user:

<%@ page language="java" %> <html> <head> <title>Name Input Form</title> </head> <body> <form method="post" action="savenametosession.jsp"> <p><b>Enter Your Name: </b><input type="text" name="username"><br> <input type="submit" value="Submit"> </form> </body>

 The above page prompts the user to enter his/her name. Once the user clicks on the submit button, savenametosession.jsp is called. The JSP savenametosession.jsp retrieves the user name from request attributes and saves into the user session using the functionsession.setAttribute("username",username);. Here is the code of savenametosession.jsp:

<%@ page language="java" %> <% String username=request.getParameter("username"); if(username==null) username=""; session.setAttribute("username",username); %> <html> <head> <title>Name Saved</title> </head> <body> <p><a href="showsessionvalue.jsp">Next Page to view the session value</a><p> </body>

 The above JSP saves the user name into the session object and displays a link to next pages (showsessionvalue.jsp). When user clicks on the "Next Page to view session value" link, the JSP pageshowsessionvalue.jsp displays the user name to the user. Here is the code of showsessionvalue.jsp:

<%@ page language="java" %> <% String username=(String) session.getAttribute("username");if(username==null) username=""; %> <html> <head> <title>Show Saved Name</title> </head> <body> <p>Welcome: <%=username%><p> </body>

The function session.getAttribute("username") is used to retrieve the user name saved in the session.

File Upload in JSP

A JSP can be used with an HTML form tag to allow users to upload files to the server. An uploaded file could be a text file or binary or image file or any document.

Creating a File Upload Form:

The following HTM code below creates an uploader form. Following are the important points to be noted down:

• The form method attribute should be set to POST method and GET method can not be used.
• The form enctype attribute should be set to multipart/form-data.
• The form action attribute should be set to a JSP file which would handle file uploading at backend server. Following example is using uploadFile.jsp program file to upload file.
• To upload a single file you should use a single <input .../> tag with attribute type="file". To allow multiple files uploading, include more than one input tags with different values for the name attribute. The browser associates a Browse button with each of them.

 
<html>
<head>
<title>File Uploading Form</title>
</head>
<body>
<h3>File Upload:</h3>
Select a file to upload: <br />
<form action="UploadServlet" method="post"
                        enctype="multipart/form-data">
<input type="file" name="file" size="50" />
<br />
<input type="submit" value="Upload File" />
</form>
</body>
</html>

This will display following result which would allow to select a file from local PC and when user would click at "Upload File", form would be submitted along with the selected file:

 
File Upload: 
Select a file to upload: 
 
 

 
 

 

NOTE: Above form is just dummy form and would not work, you should try above code at your machine to make it work.

Writing Backend JSP Script:

First let us define a location where uploaded files would be stored. You can hard code this in your program or this directory name could also be added using an external configuration such as a context-param element in web.xml as follows:

 
<web-app>
....
<context-param> 
    <description>Location to store uploaded file</description> 
    <param-name>file-upload</param-name> 
    <param-value>
         c:\apache-tomcat-5.5.29\webapps\data\
     </param-value> 
</context-param>
....
</web-app>

Following is the source code for UploadFile.jsp which can handle multiple file uploading at a time. Before proceeding you have make sure the followings:

• Following example depends on FileUpload, so make sure you have the latest version ofcommons-fileupload.x.x.jar file in your classpath. You can download it fromhttp://commons.apache.org/fileupload/.
• FileUpload depends on Commons IO, so make sure you have the latest version of commons-io-x.x.jar file in your classpath. You can download it from http://commons.apache.org/io/.
• While testing following example, you should upload a file which has less size than maxFileSizeotherwise file would not be uploaded.
• Make sure you have created directories c:\temp and c:\apache-tomcat-5.5.29\webapps\data well in advance.

<%@ page import="java.io.*,java.util.*, javax.servlet.*" %>
<%@ page import="javax.servlet.http.*" %>
<%@ page import="org.apache.commons.fileupload.*" %>
<%@ page import="org.apache.commons.fileupload.disk.*" %>
<%@ page import="org.apache.commons.fileupload.servlet.*" %>
<%@ page import="org.apache.commons.io.output.*" %>

<%
   File file ;
   int maxFileSize = 5000 * 1024;
   int maxMemSize = 5000 * 1024;
   ServletContext context = pageContext.getServletContext();
   String filePath = context.getInitParameter("file-upload");

   // Verify the content type
   String contentType = request.getContentType();
   if ((contentType.indexOf("multipart/form-data") >= 0)) {

      DiskFileItemFactory factory = new DiskFileItemFactory();
      // maximum size that will be stored in memory
      factory.setSizeThreshold(maxMemSize);
      // Location to save data that is larger than maxMemSize.
      factory.setRepository(new File("c:\\temp"));

      // Create a new file upload handler
      ServletFileUpload upload = new ServletFileUpload(factory);
      // maximum file size to be uploaded.
      upload.setSizeMax( maxFileSize );
      try{ 
         // Parse the request to get file items.
         List fileItems = upload.parseRequest(request);

         // Process the uploaded file items
         Iterator i = fileItems.iterator();

         out.println("<html>");
         out.println("<head>");
         out.println("<title>JSP File upload</title>");  
         out.println("</head>");
         out.println("<body>");
         while ( i.hasNext () ) 
         {
            FileItem fi = (FileItem)i.next();
            if ( !fi.isFormField () ) 
            {
            // Get the uploaded file parameters
            String fieldName = fi.getFieldName();
            String fileName = fi.getName();
            boolean isInMemory = fi.isInMemory();
            long sizeInBytes = fi.getSize();
            // Write the file
            if( fileName.lastIndexOf("\\") >= 0 ){
            file = new File( filePath + 
            fileName.substring( fileName.lastIndexOf("\\"))) ;
            }else{
            file = new File( filePath + 
            fileName.substring(fileName.lastIndexOf("\\")+1)) ;
            }
            fi.write( file ) ;
            out.println("Uploaded Filename: " + filePath + 
            fileName + "<br>");
            }
         }
         out.println("</body>");
         out.println("</html>");
      }catch(Exception ex) {
         System.out.println(ex);
      }
   }else{
      out.println("<html>");
      out.println("<head>");
      out.println("<title>Servlet upload</title>");  
      out.println("</head>");
      out.println("<body>");
      out.println("<p>No file uploaded</p>"); 
      out.println("</body>");
      out.println("</html>");
   }
%>

Now try to upload files using the HTML form which you created above. When you would try http://localhost:8080/UploadFile.htm, it would display following result which would help you uploading any file from your local machine.

 
File Upload: 
Select a file to upload: 
 
 

 
 

If your JSP script works fine, your file should be uploaded in c:\apache-tomcat-5.5.29\webapps\data\ directory.

Ref. => javatpoint.com

Installing the JDK and Setting the Environment Variables

Installing the JDK and Setting the Environment Variables

Want to get started with Java and set up your computer for Java, then this post is for you only. Every Java programmer I know starts off with writing the Java programs in any text editor such Notepad and compile and run it using Java tools on command line. But to make sure all goes well, you must need to install Java properly and Set up the environment variables for Java. 

Installing the Java 2 SDK (or JDK)

If you don’t have the Java 2 SDK(Software Development Kit) or simply JDK installed on your system, Follow these steps to install the JDK on your system:
1. Download the latest Java SDK version from the Oracle official site.

2. Now browse the jdk setup file on your computer and double-click on the setup file to open it. Now follow the on screen instructions to install the JDK on your system. JRE is also installed along with the JDK.
3. You can check if the JDK has been correctly installed or not by looking in the C:\Program Files\Java\. You must see the jdk1.6.0_26 folder and jre1.6.0_26 folder in it. 1.6.0_26 is the version of the jdk and it can be different depending upon which version did you download from the site.
4. Now you have successfully installed the JDK, the next step is to set the Environment Variables for your Java (JDK).

Setting up the Environment Variables

1. Right click on My Computer and click on “Properties”. Then in 
the Computer Properties window, on the left panel click on the “Advanced System Settings”, this will open the new “System Properties window.”
2. Go to Advanced tab and right down the window, click on the “Environment Variables”.
3. Now in the Environment Variables box, either you can set the variables for local user or for System variables. Local variables will only work for the current user and the System Variables will work for all the users.
4. Now for creating the variable for System Variables so that all the user can use the jdk, Find the “Path” variable in the list and click on Edit button.
5. Now place the ; followed by the path to the bin folder inside your jdk. For example  ";C:\Program Files\Java\jdk1.6.0_07\bin "
6. For local variable, you must create the PATH variable by pressing “New” button and setting its value as " ;C:\Program Files\Java\jdk1.6.0_07\bin; "
7. Now in the local variables, create a New variable “classpath” and set its value to “.” i.e. a single dot.
8. Now you are done and all ready to use the jdk for creating the java applications.

Need for Setting Environment Variables

Need for setting PATH variable:

Setting the PATH variable enables the user to use the java tools given in the bin folder from any directory on your system.
If you don’t set this variable, you can only access those tools from the bin directory only.

Need for Setting the CLASSPATH variable:

Setting the CLASSPATH variable enables your class definition to be found across all the directories. If you don’t set this variable, the program source will compile fine but will show the exception at run time that class definition not found.
So by setting the classpath variable to “.” ensures that current working directory is included in the list to found the class definition.